Baby wipes + a small 99 cent roll of TP from REI (you can do pretty much the same by pulling your roll of TP from the roller before it runs out). Bag the TP to keep it dry - a recent poll on a hiking site shows that the majority of NW hikers really appreciate a baby wipe per BM, especially on longer hikes. They get where TP just can't, not as effectively. I'll stop drawing the picture there...

btw Lono's leading economic indicator is the price of the large 36 roll toilet paper at Costco: just about a year ago you could buy it for $11.99, the checkout guy chided me for buying two. A week ago the same item was $16.99. It stands to reason: TP is by volume and weight some of the most expensive stuff to truck around the country.

another angle....maybe some of you've heard this one before...but it goes along with the belief/possiblity that the BOB might end up being something you live with and/or out of for a very long time....its the two bandana approach, one used for TP. You have to admit it will last a long time compared to one roll of TP!
My attitude toward my BOB is what if it becomes my only source for even a year? So things like soap will have to come from nature (Beech leaves, soap plants, etc.).
Of course the more you know the less you have to carry...e.g. Bushcraft and the study thereof....this approach leads the BOB as providing methods of obtaining food post the 3 day supply inside,,,,,why not learn how to build 50 different traps? many are simple variants of the other.

Some things naturally lend themselves to longer term survival, such as a good knife, a fire-making tool, a water carrier etc. Heck, there are bushmen in the tropical rain forests that use plastic grocery bags to wrap delicate items in for long periods. Short term convenience allows us time to deal with a given event. Durability provides us a means to recover, adapt, and augment further should our needs warrant it. It just makes sense, then that not everything in a BOB should be viewed as disposable.

What did humans use before there was toilet paper?

I keep a few "shoe rags" that I get when I stay in a hotel. It's a small soft cloth mitt for wiping off your shoes. They're soft, and can be washed and re-used.

I call them Star Trek Rags. They help keep the Klingons off Uranus.

The ancient Romans used a sponge on a stick....

The BOBs and other kits I've put together for DW and myself, as well as some other family members, all have have TP, wipes and soap. The more a BOB s intended to be good for only 72 or so hours, the more I'd say just have the wipes.

I like bars of glycerin soap, if I need to have soap. I like the little packs of Charmin wipes and the small rolls of TP. For the kit I recently hid in the backyard, I used a full roll of TP, a couple full-sized packs of wipes and a full-size bar of glycerin soap.